摘要:

AbstractFor a large class of non‐local, non separable potentials with non‐compact support, the solution of the radial integrodifferential equation may be reduced to the solution of a homogeneous linear integral equation of Fredholm type with a quadratically integrable kernel. In this way we derive expansions of the wave functions and the Green's function of the Schrödinger equation with a non‐local potential in terms of bound states, resonant states and a continuum of scattering functions with complex wave number. The rules of normalization, orthogonality and completeness satisfied by the eigenstates of the Schrödinger equation belonging to complex eigenvalues with ImEn<0, (Gamow or resonant states) are also derived. Finally, by means of a realistic example, it is shown how to use these expansions to exhibit the resonant behaviour of the differential cross section. Explicit expressions for the transition amplitudes and the partial widths in terms of expectation values of operators computed with Gamow functions ar

ISSN:0003-3804    

DOI:10.1002/andp.19915030802

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractWe reanalize the recently proposed proof by Jensen and Stein‐Schabes [1] of the No Hair Theorem for inhomogeneous spacetimes, putting a special emphasis on the asymptotic behaviour of the shear and curvature. We conclude that the theorem only holds locally and estimate the minimum size a region should be in order for it to inflate. We discuss in some detail the assumptions used in the theorem. In the last section we speculate about the possible measure of the set of spacetimes that would undergo inflatio

ISSN:0003-3804    

DOI:10.1002/andp.19915030803

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractA multidimensional generalization of the Reissner‐Nordström solution of general relativity is obtained for the case ofnRicci‐flat internal spaces. A two‐parameter family of black‐hole solutions for an arbitrary dimensionalityDis selected. Nontrivial black holes withD>4 are shown to exist only with a nonzero electric charge. Observational consequences are discussed, in particular, a violation of Coulo

ISSN:0003-3804    

DOI:10.1002/andp.19915030804

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractUsing a shock wave ansatz, first, the fourth‐order jump problem in gravitational theories containing fourth derivatives of the metric is investigated and, second, the obtained results are generalized for arbitraryn‐order jumps. For fourth‐order jumps, in particular, the dynamic modes of the field are ana

ISSN:0003-3804    

DOI:10.1002/andp.19915030805

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe first part of this work reviews problems of (particle and field) theories with higher than second time derivatives. The second part gives an overview about the known results concerning the structure of bosonic field theories with at most second order equations.

ISSN:0003-3804    

DOI:10.1002/andp.19915030806

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractIt is argued that, due to the cut‐off lengths arising in Quantum General Relativity,R2corrections of Einstein's theory cannot be interpreted as quantum correction

ISSN:0003-3804    

DOI:10.1002/andp.19915030807

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractIt is shown that — within the framework of an idealized model with taking into account backscattering at density fluctuations — there is a numberNKof atoms such that for an atomic numberN≫NKforward‐backward independence will be found whileN≪NKleads to synchronized superfluorescence pulses in both d

ISSN:0003-3804    

DOI:10.1002/andp.19915030808

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe joint probability of detecting simultaneously three photons at two and three points in the superposition field of three independent plane waves with the same frequency but random phases is calculated and compared with the results of a classical wave theory. Significant differences occur for sufficiently weak fields. We find that the differences between the quantum mechanical and classical predictions concerning the third order intensity correlation functions are more pronounced in a three‐beam than in a two‐beam interference experim

ISSN:0003-3804    

DOI:10.1002/andp.19915030809

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractBorn und Ladenburg bemerkten bereits 1911, daß bei der Reflexion und Transmission elektromagnetischer Wellen durch eine Grenzfläche zwischen zwei verschieden stark absorbierenden Medien außer den mit den laufenden Wellen verbundenen Poyntingvektoren noch ein zur Erfüllung der Energiebilanz an der Grenzfläche notwendiger, sog. „gemischter”︁ Poyntingvektor zu beachten ist. Die mit diesem Vektor beschriebene Energieströmung ist stets dorthin gerichtet, wo aus derselben mehr Energie absorbiert wird. Sie entsteht im Zusammenhang mit einer räumlichen Modulation des Energieverbrauchs im partiell stehenden Interferenzfeld der einlaufenden und der reflektierten Welle, wobei die Energieabsorption bei den meisten Substanzen durch das elektrische Feld erfolgt, während das Magnetfeld daran praktisch unbeteiligt ist.Da jedoch die Mitberücksichtigung der magnetischen Effekte zum besseren Verständnis des gemischten Poyntingvektors beitragen kann. wird im folgenden zu ihrer quantitativen Beschreibung in die zweite Maxwellsche Gleichung ein dem Stromglied in der ersten Maxwell‐Gleichung analoger Zusatzterm eingeführt. Die Amplitude des „gemischten”︁ Poyntingvektors erweist sich dann als wesentlich abhängig vom Verhältnis der elektrischen zu den magnetischen Verlusten. Dies wird durch Betrachtung eines Mediums verdeutlicht, in welchem außer den Verlusten durch das elektrische Feld auch hiermit vergleichbare Verluste über das Magnetfeld auftreten, wobei beide Verlustarten zusammen eine an die räumliche Verteilung der Feldenergie besser angepaßte Absorption ergeben. Bei gleichen Energiedichten und Energieverlusten des elektrischen und des magnetischen Feldes verschwindet d

ISSN:0003-3804    

DOI:10.1002/andp.19915030810

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe intensity noise spectrum is investigated quantum‐mechanically for incident coherent light passing through a resonator which is filled with ak‐photon‐absorber. Fork⩽ 2 the noise of the outgoing light is reduced below the shot noise level the reduction being maximal for frequencies that are small in comparison to the cavity bandwidth. It turns out that the highest possible value of this low‐frequency noise reduction is obtained when the resonator losses due to transmission through the outcoupling mirror are 2k– 1 times as large as thek‐photon absorption losses. In this case the noise at zero frequency is reduced with respect to the shot noise level by a facto

ISSN:0003-3804    

DOI:10.1002/andp.19915030811

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY